1. Field of the Invention
This invention relates to an electric control system with mechanical interlocks for preventing closing of two or more circuit breakers at the same time.
2. Description of the Prior Art
The control of electrical equipment, such as reversible and multispeed motors, usually includes a circuit interrupter for each motor operation. A typical circuit includes, for example, a separate manual button for each circuit interrupter for the forward and reverse directions of a motor. Moreover, actuation of a forward or reverse circuit includes an associated circuit for deactivating another of the forward and reverse circuits. Notwithstanding such precautions, it sometimes occurs due to inadvertence or other reasons that both circuits, i.e., forward and reverse control buttons are actuated simultaneously and thereby cause incorrect phase-to-phase line connections in the interrupters.
Associated with the foregoing is a problem with some circuit control systems where two supply lines are provided, such as, normal and emergency supply circuits. Where in addition a bypass circuit is provided to allow for maintenance of part of the control system it is particularly desirable to provide in addition mechanical interlocks for the safety of maintenance personnel.